The present invention relates to the field of endodontic instruments for the reaming of tooth canals, and more particularly, to a specific instrument for reaming tooth canals and a sequence of instruments comprising at least one such specific instrument.
Endodontic treatment involves a mechanical reaming of the root canal, followed by filling of the root canal, which is the final desired objective. Filling is done by adding an external material, for example, gutta-percha.
The gutta-percha is usually introduced into the prepared root canal in the form of a heated cone. Heating causes the gutta-percha to soften, rendering it malleable. The heated cones are condensed by mechanical action, with the aid of a rammer, in order to bring about “vertical” condensation or “lateral” condensation of the material relative to the longitudinal axis of the reamed root canal. The gutta-percha can also be arranged in the canal using the devices which are described in U.S. Pat. No. 5,588,835 or International Publication No. WO 93/14714.
Such techniques, and their purpose, are well known to the person skilled in the art and are widely used on a daily basis by practitioners.
In the operations performed for the mechanical preparation of a root canal, the practitioner generally attempts to preserve the anatomy of the root canal to the extent possible, in particular, to avoid weakening of the root as a result of an excessive removal of substance. The tendency is, therefore, toward minimum reaming of the canal. When this objective is observed, the result is a conical preparation having a small diameter at the apical level.
As a consequence of this, it is sometimes difficult to obtain a good filling with the methods described above. This is because such methods generally require, on the one hand, a wide canal preparation and, on the other hand, provision at the bottom of the canal of a seat-like bore which avoids the risk of the gutta-percha leaving the canal as a result of creep. It is, therefore, necessary to find a balance between these two constraints so as not to exaggerate the preparation in the upper part of the canal, which has the consequence of weakening the upper part of the canal.